Can you find lost Nodes in the Node Editor?
If Blender crashes while centering the Node editor on the selected node then they are indeed moved to infinity and it's some sort of a bug so at least compositing might be better to be redone. 

Still there's a way to move one node from somewhere you don't see to another one you can actially see with snapping in the Node Editor (just like in 3d viewport) with Shift+Tab and then choosing element to snap to. 

With the node somewhere far away selected, choose Snap To X/Y to snap selected node to any border of the node to snap to. Then press G to move selected node and hover mouse over the node which is seen in the editor.



With this way the node from somewhere away will be moved to the current 2d viewport position. 

It's also possible to select all the nodes, press S to scale and enter 0 to move them all to the same place (like written in your question), but the pivot point will be somewhere between the selected nodes so that's where they will be moved to (actually it might be not really important). Hence after scaling with nodes still selected press Numpad . (period) and you should see the nodes in the center of the editor.